In the development history of robot controller, based on the control architecture, robot controllers can be classified into different categories, i.e. a robot controller can be in a single CPU structure, a centralized control architecture, a two-level CPU structure, a master-slave control architecture or a multiple CPU distributed control structure, etc. The first two structures were developed in the earlier stage of the development of computer technology, and they were realized by employing microprocessor units wherein the computing power of the CPU is not sufficiently powerful. The third structure generally applied the form of PC plus DSP-based motion control card (for example, PMAC card or Trio board card) which were respectively used to execute the upper computer programs and the motion control programs.
However, these solutions have some similar problems, i.e. their structures being relatively complicated, the programming being difficult, and the system computing power being weak, which bring difficulties in carrying out complicated calculations like dynamic control of a robot; the connection of the software and the hardware being relatively close; the wiring being complex, and the debugging and maintenance of the system being difficult, which result in an unreliable system. Furthermore, with the increase of targets to be controlled, the control of targets would become extremely difficult. Where a coordinated control of more axes is required, a significant adjustment of the entire structure would be needed, which would result in an increase of costs.
The latest open architecture is described, for example, in Chinese patent application CN1424649A titled “Open architecture robot controller”. Although the open controllers were developed using a real-time system on a PC, such controllers are basically of an architecture having levels and each of the levels is employed to carry out a predetermined function. Where a new function is required, the architecture of the system is generally required to be modified and this is labor consuming.